White material shows up as gray regardless of lighting
I looked at both files and the only difference really is that you got rid of the camera and light in the wrecking ball file.

If that is the only thing you want to change:


Load the "rigid body sim.blend" file.
Switch the render engine to cycles to get the same result and switch to render view!
Go in the file menu and select "Append..."
Find and double click the "default.blend" file to open up it's content to chose from.
Go in the "Objects" folder and select "Camera" and "Light"
Confirm to load.
In the scene the two new objects are hidden inside the cubes, so select them and scale them (yes scale, will only scale them in regard of position from world center) far enough to have a good view. Check by switching to the camera view.
Now select the light and increase it's Power from 1000 to something like 10000+..
Go from there and you should be fine.


Here the visual aid/explanation: